JPS5922662Y2 - oil-filled bushing - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement in oil-filled bushings used in gas-insulated electrical equipment.

Generally, the gas pressure of insulating gas inside gas-filled electrical equipment is 3
It is used at a pressure of ~4 kg/cm2.

However, the internal pressure of oil-filled bushings used in gas-insulated electrical equipment is 0.5 to 1.0 kg/cm2.
This is considerably lower than the pressure on the gas side, so if the sealing effect of the backing etc. deteriorates over time, there is a risk that gas may infiltrate into the bushing.

Figure 1 shows the structure of a conventional bushing, where 1 is an insulating tube on the gas side, 2 is an insulating tube on the atmosphere side, 3 is a flange for fixing the bushing to gas-insulated electrical equipment, and 4 is both the above-mentioned insulating tubes 1. , 2 and a center conductor passing through the flange 3; 5 an insulating layer insulating the center conductor; 6 a terminal fitting screwed to one end of the center conductor 4; 7 used at the other end of the center conductor 4; An expansion chamber having a bellows 7a communicating with the surface pipe and capable of absorbing expansion and contraction; 8 a compression spring; 9 a stop plate; 10 screwed to the center conductor 4 so as to compress the compression spring 8; A compressive force is applied to the insulating tubes 1, 2 and the flange 3 by a tie ring.

11.12 is the seal that seals between gas and oil, 1
3.14 is the seal that seals between oil and air, 1
5 is insulating oil inside the bushing.

Reference numeral 16 indicates one end of the gas insulated equipment, 17 indicates a gas section in the gas insulated equipment, and 18 indicates an O-ring for sealing the same.

In such a structure, due to aging of the gas side gaskets 11 and 12, the high pressure gas 17 is transferred to the gas side gaskets 11 and 11.
2, etc., into the bushing.

Gas that has entered the bushing will be dissolved in the oil to some extent, but once it exceeds a certain limit, it will form bubbles and rise upward through the oil.

When these bubbles are present in an electric field, the electric field strength at the bubble increases because gas has a smaller dielectric constant than oil, causing partial discharge, which causes deterioration of the bushing and dielectric breakdown of the entire bushing.

Furthermore, if gas leakage continues, the internal pressure of the bushing will eventually rise to the same gas pressure as that of the gas-insulated equipment, and there is a risk that the bellows 7a will be destroyed.

This invention was devised in view of the above points, and is intended to provide an oil-filled bushing that does not allow high-pressure gas, which is difficult to seal, to enter the bushing.

FIG. 2 shows an embodiment of this invention, and parts corresponding to those in FIG. 1 are designated by the same reference numerals and detailed description thereof will be omitted.

19 is a second gas side insulating tube provided on the outer periphery of the gas side insulating tube 1, 20.21 is a gas side packing, gas side insulating tube 1,
Insulating oil 22 is sealed in the gap 19.

The bushing flange 3 has a bellows 23 and an oil container 24.
Attach the pressure suppressor consisting of the gas side insulating pipe 1
The insulating oil 22 in the gap between the second gas-side insulating pipe 19 and the second gas-side insulating pipe 19 are communicated with the oil container through an oil pipe 26.

In addition, the inside of the bellows 23 is provided with a gas section 17 by a vent hole 27.
The bellows 23 is filled with gas from the gas insulated equipment.

With this structure, volume changes due to temperature changes in the insulating oil 22 are absorbed by the expansion and contraction of the bellows 23, and the gas pressure of the gas section 17 is constantly applied via the bellows, so that the pressure of the insulating oil 22 is is always equal to the pressure in the gas section 17.

Therefore, the gasket 20 on the end face of the second gas side insulating tube 19
．． The pressure inside and outside of the 21st part is the same, and the gas is
．． 21 into the bushing, and the second gas side insulating tube 19 is also thin and does not have much mechanical strength.

The insulating oil 22 outside the gas side insulating tube 1 has the same pressure as the gas pressure, but sealing the insulating oil is much easier than sealing gas, so the gasket H1 on the end face of the gas side insulating tube 1 , 12 is extremely easy to design, and the reliability of the seal is extremely high.

In addition, if the electric contact 25 is installed between the bellows 23 and the oil container 24 and adjusted so that it does not work due to the expansion and contraction of the bellows 23 due to the expansion and contraction of oil, it is possible to prevent the insulating oil 22 from entering the bushing from gaskets 11 and 12 It can be easily detected even if it invades.

However, in this case, since the amount of insulating oil 22 is smaller than the insulating oil 15 in the bushing, the internal pressure of the bushing increases only slightly, and the insulation does not deteriorate or deteriorate.

Furthermore, according to the present invention, even if insulating oil intrudes from the gaskets (11 and 12), the insulating oil in the bushing can be extracted by the intruding amount and refilled into the oil container 24, and the oil container 24 can be used as is. No need for maintenance,
This makes management extremely easy.

In addition, although the above description has been given as an example of a bushing used in the atmosphere, exactly the same effect can be expected when the atmosphere-side insulating tube 21 is used in insulating oil.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional oil-filled bushing, and FIG. 2 is a sectional view showing an embodiment of this invention. In the figure, 1 and 19 are gas side insulated tubes, 2 is atmospheric side insulated tubes, and 3
is flange, 11.12.20.21 is packing, 22
23 is an insulating oil, 23 is a bellows, 24 is an oil container, and 25 is an electrical contact. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (2)

[Scope of utility model registration request] (1) In an oil-filled bushing used for gas-insulated electrical equipment, the insulating tube on the gas-insulated equipment side is double-shaped, the gap between the insulating tubes is filled and sealed with insulating oil, and the volume change of the insulating oil is absorbed and deformed. An oil-filled bushing characterized by having a bellows inside the gas. (2) The oil-filled bushing according to claim 1, which is characterized by being provided with an alarm device for detecting dimensional changes in the bellows.